Using wing morphology to separate four species of Acrocephalus warblers in Scandinavia

Abstract

The unstreaked Acrocephalus warblers can be challenging to identify, even in the hand. Previous studies have highlighted wing length, second-primary notch length, and second-primary notch position as criteria for separating Eurasian Reed Warbler A. scirpaceus and Marsh Warbler A. palustris. We present data for wing length, second-primary notch length, and second-primary notch position for Blyth's Reed Warbler A. dumetorum and Paddyfield Warbler A. agricola, obtained from museum skins, to complement data published previously for Scandinavian populations of Eurasian Reed Warbler and Marsh Warbler. These data provide a reliable and non-subjective method for the separation of Blyth's Reed Warbler and Paddyfield Warbler from Eurasian Reed Warbler and Marsh Warbler in Scandinavia.